The invention relates generally to a method and apparatus used in underground pilings in the field of foundation repairs, for aiding a grouting substance to continue flow down a piling passageway rather than collecting in an upper portion of the passageway.
One of the older methods for repairing foundations of buildings having slab-on-ground foundations uses drilled underground piers. Holes are drilled approximately eight to twelve feet in depth and filled with concrete. After the concrete has dried, jacks are placed on top of the pier and the foundation is brought to a level position. The jack is replaced by blocks, shims, and grout. A less expensive method is the use of driven precast solid concrete cylindrical pile sections, which are approximately one foot in height and six inches in diameter. These sections are driven into the earth one on top of the other to form a column or stack of concrete cylinders. The depth to which the bottom of the pier is driven into the earth depends upon the type of soil and zone of the seasonal moisture change. A cylinder having a larger diameter, or a pile cap, is a placed on top of the previously driven sections. Jacks are placed on top of the pile cap and the foundation is lifted.
The precast pile method relies upon the skin friction with the soil for its strength. It has the advantage of being faster since the concrete does not have to cure and precasting allows better control of concrete strength. A major disadvantage is that the one foot cylindrical sections may shift and become misaligned. Different methods have been proposed for maintaining alignment between sections. One of the methods involves pouring a grouting substance into a passageway running through all the piling segments. The grouting material sometimes collects along the passageway before the grout has filled the portions of the passageway below the collecting grout. The collecting grout causes the area though which the grout can flow to narrow and close, thereby preventing the grout from filling the entire passageway. Without the grout filling the entire passageway, the piling segments having passageways that the grout could not fill are able to slip out of alignment.
The method in this invention is used for securing a plurality of piling segments together in order to form a foundation piling. Piling segments are driven into the ground on top of each other to form a piling. The number of piling segments is a function of the type of earth and the relative water levels of the surrounding area. The piling segments each have a passageway running axially through the segments that aligns so that there is a single passageway running through the piling. The segments are secured by an alignment securing assembly so the segments do not slip or move out of alignment after the piling segments are driven into the ground. The segments may have an outer metallic sleeve that extends around the circumference of the piling segments.
Vibrations are sent through the piling. Grout is poured into the passageway to increase the compressive and tensile strength of the piling. Grout is prevented from collecting in upper portions of the passageway before the grout fills the portions of the passageway below. One means of producing the vibrations sent through piling is forming a hole along side the piling and placing a vibration rod into the hole so that the lower portion of the rod is substantially in contact with the upper portion of the piling. The upper end of the vibration rod is connected to a vibratory device, which sends vibrations through the vibration rod and causes the vibration rod to vibrate substantially against the piling. Another means of preventing the grout from collecting in the upper portions of the passageway is to place a support member in the passageway and then send vibration through the support member with a vibration rod that is substantially in contact with the support member.
One of the alignments securing assemblies is an anchoring device. The anchoring device in this invention is used to in conjunction with a cable in tension to apply compression to a foundation piling. The compressive state of the foundation piling helps to prevent the individual segments of the foundation piling from slipping or sliding out of alignment. The anchoring device is suspended by a cable into a piling passageway running through all the piling segments. After the anchoring device is lowered to a desired depth, a weight is dropped onto the anchoring device. The force of the weight hitting the anchoring device causes the anchoring device to expand and grip the passageway of the piling. The surface of the anchoring device is textured to prevent the anchoring device from slipping from the piling. A piling assembly is defined with the piling segments and the cable once the cable is anchored to the piling in the piling passageway with anchoring device.
Then tension is applied to the cable. The upward force from the tension is communicated through the anchoring device and into the piling. The upward forces exerted on the lower portion of the piling causes a compressive effect between the upper portion of the piling and the lower portion of the piling. This state of compression helps to prevent the piling segments from sliding relative to each other.